1. Field of the Invention
The invention relates in general to a motion estimation method, and more particularly to a motion estimation method employing a weighted SAD operation that is provided to emphasize absolute differences corresponding to high-frequency pixels within the current macroblock.
2. Description of the Related Art
Motion estimation is essential to video compression like MPEG and H.26x video compression. The motion vector for a current macroblock might be estimated using an SAD (sum of absolute difference) operation provided to equally accumulate pixel-by-pixel absolute differences between the current macroblock and each of the reference macroblocks in the previous frame.
The reference macroblock having the lowest SAD output could be determined as the matched macroblock, so that the displacement between the matched macroblock and the current macroblock can be defined as the motion vector for the current macroblock. However, the SAD operation used in the conventional motion estimation method equally accumulates the pixel-by-pixel absolute differences for both high-frequency and low-frequency pixels, which would tend to estimate the motion vector mistakenly due to luminance change and noise interference between different frames. Therefore, it is highly desired to provide a new motion estimation method, which could accurately determine the matched macroblock and thus the motion vector.